Production and fate of the G ring arc particles due to Aegaeon (Saturn LIII)

Abstract

The G ring arc hosts the smallest satellite of Saturn, Aegaeon, observed with a set of images sent by Cassini spacecraft. Along with Aegaeon, the arc particles are trapped in a 7:6 corotation eccentric resonance with the satellite Mimas. Due to this resonance, both Aegaeon and the arc material are confined to within sixty degrees of corotating longitudes. The arc particles are dust grains which can have their orbital motions severely disturbed by the solar radiation force. Our numerical simulations showed that Aegaeon is responsible for depleting the arc dust population by removing them through collisions. The solar radiation force hastens these collisions by removing most of the 10 µm sized grains in less than 40 years. Some debris released from Aegaeon's surface by meteoroid impacts can populate the arc. However, it would take 30,000 years for Aegaeon to supply the observed amount of arc material, and so it is unlikely that Aegaeon alone is the source of dust in the arc.

Dynamical stability in the vicinity of Saturnian small moons. The cases of Aegaeon, Methone, Anthe and Pallene

“…Moreover, we obtained arcs with longitudinal sizes similar to the observed ones, at least for Methone and Anthe. When also non-gravitational forces are considered the lifetime of the particles is size dependent, with grains larger than 5 µm surviving in the arcs of Methone and Anthe for 10 2 yr (Sun et al 2017), whereas particles of 10 µm have a lifetime of 26 yr in the arc of Aegaeon (Madeira et al 2018). These results together put constraints on the timescales for which gravitational and non-gravitational forces operate to remove particles from the arcs.…”

“…Hedman et al 2009). However, the consideration of non-gravitational forces have shown that most particles are removed from the arcs in timescales of dozens of years, depending on the size of the grain (Sun et al 2017;Madeira et al 2018;Madeira & Giuliatti Winter 2020), indicating that the origin and sustainability of the arcs is still a puzzle (see also Araujo et al 2016).…”

“…However, we are not establishing a direct relationship between the clumps obtained in our simulations with the observed arcs. Indeed, previous works have investigated the formation and sustainability of arcs structures around Aegaeon, Methone and Anthe considering gravitational and non-gravitational perturbations (Araujo et al 2016;Sun et al 2017;Madeira et al 2018). In Sec.…”

“…As we mentioned in Sec. 3.6, previous works have investigated the formation and sustainability of arcs structures around Aegaeon, Methone and Anthe considering gravitational and non-gravitational perturbations (Araujo et al 2016;Sun et al 2017;Madeira et al 2018). Note that Madeira & Giuliatti Winter (2020) claim that, due to instabilities of the dust particles, the arcs tend to be transient structures.…”

Analysing the region of the rings and small satellites of Neptune

“…The material ejected can feed a tenuos ring. By assuming the impactors mass flux at Neptune's region as F ∞ imp = 10 −17 kg/(m 2 s) and the mean velocity of the impactors as v ∞ imp = 3.0 km/s (Poppe 2016), we determined the mass flux F imp and velocity v imp of impactors enhanced by to the gravitational focusing of the planet through the algorithm described in Sfair and Giuliatti Winter 2012 andMadeira et al (2018). The mass production rate by an icy moon with radius R is (Koschny and Grün 2001; Krivov et al 2003) Figure 11 shows the mass production rate of the neptunian inner satellites Naiad, Thalassa, Despina, Galatea, Larissa and Proteus.…”